Clinical studies related to cardiac pacing have shown that an optimal atrioventricular pacing delay (e.g., AV delay or PV delay) can improve cardiac performance. However, such optimal delays depend on a variety of factors that may vary over time. Thus, what is “optimal” can vary over time. An optimization of AV/PV pacing delay may be performed at implantation and sometimes, a re-optimization may be performed during a follow-up consultation. While such optimizations are beneficial, the benefits may not be long-lasting due to changes in various factors related to device and/or cardiac function.
The following patents and patent applications set forth various improved systems and methods for, inter alia, allowing a pacemaker or ICD to determine and/or adjust AV/PV pacing delays (as well as interventricular (VV) pacing delays) so as to help maintain the pacing delays at optimal values: U.S. Pat. No. 7,248,925 to Bruhns et al.; U.S. patent application Ser. No. 10/703,070, filed Nov. 5, 2003, now abandoned; U.S. patent application Ser. No. 10/974,123, filed Oct. 26, 2004 now abandoned; U.S. patent application Ser. No. 10/986,273, filed Nov. 10, 2004 now U.S. Pat. No. 7,590,446; U.S. patent application Ser. No. 10/980,140, filed Nov. 1, 2004 now abandoned; U.S. patent application Ser. No. 11/129,540, filed May 13, 2005 now abandoned; and U.S. patent application Ser. No. 11/952,743, filed Dec. 7, 2007 now abandoned.
In particular, techniques were set forth therein for exploiting inter-atrial conduction delays to set optimal or preferred AV/PV pacing delays to time the delivery of ventricular pacing pulses (V-pulses). It would be desirable to provide additional or alternative techniques for setting AV/PV pacing delays.
In particular, it is desirable to provide improved techniques for detecting the boundaries of atrial events for use in setting the AV/PV delays. In at least some of the patents and patent applications cited above, near-field atrial signals are sensed using electrodes implanted within the atria to detect P-waves (i.e. intrinsic atrial depolarization events) for use in determining the inter-atrial conduction delay of the patient, from which the duration of preferred AV/PV pacing delay intervals are set. Also, some implantable devices trigger the timing of particular AV/PV intervals (for use in delivering particular V-pulses) based on the end of the latest P-wave. However, since atrial electrodes detect atrial activity locally around the electrodes, near-field atrial activity sensed using an atrial electrode might not properly represent the actual timing of atrial events across both the right and left atria. Hence, neither the determination of the preferred duration of the AV/PV pacing delay intervals, nor the triggering of particular AV/PV timing intervals for use in delivering particular V-pulses, is optimal when using near-field atrial activity.
Accordingly, it is desirable to provide systems and methods exploiting far-field atrial signals for use in detecting atrial events for use in setting and using AV/PV pacing delays and it is to this end that aspects of the present invention are directed.